Heat traps for hot water storage tanks are known. The traps are mounted at the outlet, and often at the inlet of the tank to minimize convection losses from the tank, when hot water is not being drawn off.
Many of the known traps, of which U.S. Pat. No. 4,286,573 is an example, employ a ball valve to prevent the convection losses. Such traps are however relatively expensive because of the number of parts employed. In addition, the valves can be mounted in only one specific manner if they are to be effective. To ensure that the valves are properly mounted, they must be suitably marked leading to additional cost, and even when marked, they could still be installed improperly. Ball valves also employ balls of different density depending on whether the valve is to be mounted on the outlet or inlet of the tank. Thus different valves are required for the different locations where it can be mounted on the tank, making the use of these valves still more expensive. Ball valves often have slits or openings in the seat of the valve to provide pressure relief. These slits or openings however can become blocked with sediment or deposits in hard water conditions. In addition, the slits or openings permit some convection losses, which losses the ball valves are supposed to minimize.
Other known heat traps employ no moving parts. Instead a convoluted water channel is provided within the trap with a portion of the channel allowing cooling of the water therein which cool water blocks the flow of warmer water from the tank. An example of such a trap is shown in U.S. Pat. No. 3,144,904. This type of trap is cheaper than a ball valve type since it has no moving parts. However these traps are to be mounted in one specific manner only and can usually be only used at the hot water outlet. In addition, these traps can usually be easily disassembled which can cause parts to be easily lost. Further, these traps usually have numerous sharp corners and crevices in the water channel that can lead to the trapping of sediment and deposits and eventual blockage of the trap.